In the Ask This Old House loft, Tom Silva shows host Kevin O'Connor how to build a simple workbench. Roger, Kevin O'Connor, Richard Trethewey and Tom Silva examine an unfamiliar object and try to guess how it is used. Roger then gives Kevin tips on h... (more)ow to tune-up a gas-powered lawn mower. Then Richard silences a whistling forced-air heating system by installing a bypass duct.